Sir Robin is also known by its systematic name 282P6H2V1, and is alternatively called seahorse or Minstrel 0 / M0 (see Tagalongs below). It is based on a partial found by Tomas Rokicki, which makes up about 62% of the ship,[1] and which was itself an independent rediscovery of roughly half of a partial found by Josh Ball in April 2017.[2] Sir Robin is the first elementaryknightship in Conway's Game of Life. A scientific paper describing the method used to find the ship is forthcoming.[3]

Synthesis

No glider synthesis for Sir Robin exists as of March 10, 2018; finding a synthesis is considered a challenging task at best, due to the large size of the ship, and the amount of space dust it contains.

The complete spaceships are named Minstrel 0 (Sir Robin) through to Minstrel 15 and Minstrel 18, agreeing with order of discovery up to Minstrel 10 and departing slightly thereafter. The elementary components are given the following names:

Sir Robin := Minstrel 0

Errant minstrel := Minstrel 1 - Minstrel 0

Lightweight minstrel := Minstrel 2 - Minstrel 0

Heavyweight minstrel := Minstrel 3 - Minstrel 0

Wandering minstrel := Minstrel 5 - Minstrel 3

Ragged minstrel := Minstrel 6 - Minstrel 2

Featherweight minstrel := Minstrel 9 - Minstrel 6

Pi minstrel := Minstrel 10 - Minstrel 3

Connecting minstrel := Minstrel 11 - Minstrel 5

Fountain minstrel := Minstrel 12 - Minstrel 1

Several of these "elementary minstrels" are not technically true tagalongs, because they slightly modify the trailing sparks on the spaceship to which they attach.

History

Dave Greene modified Martin Grant's Sir Robin eater to act as a Minstrel 1 detector the same day, which removes the errant minstrel to yield the original Sir Robin.[7]

On July 19, 2018, Adam P. Goucher found a second and third minstrel, dubbed Minstrel 2 and Minstrel 3, that follow Sir Robin more closely. The lightweight and heavyweight minstrels are not true tagalongs because they change the evolution of the Sir Robin itself.[8]

On July 20, 2018, Goldtiger997 built a stable circuit that can accept any of Minstrel 0 through to Minstrel 3,[9] emitting a glider in one of four directions (depending on the input spaceship) along with an unadorned Sir Robin travelling along the original path. When the original input is a Sir Robin, this circuit is a Heisenburp; otherwise, it is a downconverter. The circuit was later optimised by including a bend in the 2c/3 signal wire, among other bounding-box reductions.

On Christmas Day in 2018, Entity Valkyrie discovered that the heavyweight and errant can be composed, yielding Minstrel 4[10]. Two days later, Goldtiger997 updated the previous minstrel remover/detector to accept any of the known tagalongs including the composite Minstrel 4.[11]

The following month a further tagalong, Minstrel 6, was discovered by the ikpx search program, and was added to existing components to produce two new spaceships, Minstrels 7 and 8. Minstrel 9 followed shortly after, on the 18th January, and another "pi minstrel" tagalong was discovered on the 21st of January which created Minstrels 10 and 13. A longer tagalong discovered in early February produced Minstrels 11 and 14 in the same way, and also enabled much simpler branching knightships. The following day a tagalong to the errant minstrel was discovered, yielding Minstrels 12, 15, and 18.

Minstrel arithmetic

Due to increasingly large liberties taken with the initial chronological numbering (beginning with the dicovery of minstrel 13), the relationships between these spaceships can be encapsulated by 'minstrel arithmetic': the observation that integer 'weights' can be assigned to Sir Robin and its indecomposable tagalongs such that the sum of the weights of the components of Minstrel n is exactly n:

If direct connections to the left and right sides of Sir Robin spaceships are included, (2,1)c/6 technology now allows branching spaceships, since it is possible to make connections in three directions from a single spaceship. The known direct connection between two Sir Robin spaceships makes a slightly steeper angle than a knightwave -- (15, -13) instead of (5, -3). This means that any added branch on the left side (as in the example shown above) runs out of space after six direct connections have been made. However, direct-connection branches on the right eventually allow additional three-way branch points to be connected.[13] The "connecting minstrel" enables another type of branching-spaceship connection with much more clearance.[14]

Thus every known (2,1)c/6 spaceship is either:

Minstrel n (for some n between 0 and 15, as well as 18), or

A sequence of two or more spaceships, each of the above form, with adjacent spaceships joined by one of two types of connections:

a horizontal segment of knightwave containing any sufficiently large number of repeating components (where 'sufficiently large' is such that the two knightships do not interact, i.e. 3 units), or

a direct diagonal connection between two Sir Robin spaceships, changing the position of one cell along the connected edge for a single tick (compare the right edges of the two directly connected Sir Robins at T=0 in the example above), or

a connection between the tail of Minstrel 14 and the direct-connection point on any Minstrel 0 to 15 (or 18), or

a branching spaceship consisting of multiple connected sequences as described above.

The leftmost spaceship in a knightwave sequence must contain either a lightweight or heavyweight minstrel, and the remaining spaceships must all contain lightweight minstrels.